#include<bits/stdc++.h>
#define int long long
#define endl '\n'
using namespace std;
const int mod=998244353,inf=0x3f3f3f3f3f3f3f3f;
const int N=2e5+10,M=2e2+10;
mt19937 rnd(time(0));
int n,m,q,k;
int f[N][M];
inline void add(int &x,int v){x=(x+v)%mod;}
signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
	freopen("sequence.in","r",stdin);
	freopen("sequence.out","w",stdout);
	cin >> n>> m >> q >> k;
	if(q<m)return cout << 0,0;
	f[0][0]=1;
	for ( int i = 0 ; i < q ; i++ )
		for ( int j = 0 ; j <= m ; j++ )
			add(f[i+1][j],f[i][j]*(n-m+j)%mod*k%mod),
			add(f[i+1][j+1],f[i][j]*(m-j)%mod);
	cout << f[q][m]*(n-m+1)%mod;
	return 0;
}


